This application is based on Japanese Patent Application Nos. 2001-310648, 2001-310647 and 2001-310646 filed Oct. 5, 2001, and Nos. 2001-398215 and 2001-398214 filed Dec. 27, 2001, the content of which are incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a liquid container, a liquid supplying apparatus, and a recording apparatus for supplying a liquid such as ink to a pen or recording head as a recording section, for example, in an efficient and stable manner, and to an ink jet cartridge.
2. Description of the Related Art
Ink jet recording apparatuses that form an image on a recording medium by applying ink that is a liquid to the recording medium using a liquid consuming or using apparatus such as an ink jet recording head include apparatus that form an image by ejecting ink while moving a recording head relative to a recording medium and apparatus that form an image by ejecting ink while moving a recording medium relative to a fixed recording head conversely.
Methods of supplying ink to a recording head used in such an ink jet recording apparatus include a method referred to as on-carriage method in which an ink tank is integrally or separably mounted to a recording head that is carried by a carriage to be moved back and forth (main scanning) and in which ink is directly supplied from the ink tank to the recording head. There is another method referred to as tube supply method in which an ink tank is fixed in a region of a recording apparatus other than a carriage as a body separate from a recording head carried by the carriage and in which ink is supplied by coupling the ink tank and the recording head through a flexible tube. The method includes a configuration in which a second ink tank to serve as an intermediate tank (sub-tank) between an ink tank (main tank) and a recording head is mounted on the recording head or a carriage and in which ink is directly supplied from the second ink tank to the recording head.
According to those methods, an ink tank to supply ink to a recording head directly is provided with a mechanism for generating an adequate negative pressure in a range in which the negative pressure is in equilibrium with a pressure in the recording head to hold meniscuses formed at an ink ejecting section thereof to prevent the ink from leaking from the ink ejecting section satisfactorily and in which an ink ejecting operation of the recording head can be performed.
In a negative pressure generating mechanism of this type, a porous member such as a sponge that is impregnated with ink to be held thereby is contained in an ink tank, and an adequate negative pressure is generated by an ink holding capacity of the same.
In another mechanism, a bag-shaped member formed from a material such as rubber having an elastic force and generating a tension in the direction of increasing the volume thereof is charged with ink as it is, and the tension generated by the bag-shaped member exerts a negative pressure to the in therein.
In still another mechanism, a bag-shaped member is formed using a flexible film, and a spring for urging the film in the direction of increasing the volume of the bag-shaped member is bonded to the interior or exterior of the same to generate a negative pressure.
In any of the above mechanisms, however, the negative pressure tends to increase as the amount of ink in the ink tank decreases, and it becomes impossible to supply ink to a recording head stably when the level of the negative pressure exceeds a predetermined value. This results in a problem in that the ink tank becomes unusable before the ink is completely used up.
For example, there is Japanese Patent Application Publication No. 3-024900 (1991) which discloses a structure of an ink tank of a type which is constituted by a flexible enclosed bag-shaped member that directly contains ink therein and that can be deformed according to the amount of contained ink and in which a spring member is provided in the bag-shaped member. Since the negative pressure is basically determined such that the spring force and a force resulting from the negative pressure (or a difference between the atmospheric pressure and the negative pressure) are balanced with each other, the negative pressure in the bag-shaped member increases as the deformation of the spring proceeds with the deformation of the bag-shaped member as a result of ink consumption. This may result in a problem in that the negative pressure increases beyond a proper range in which an ink ejecting operation of the recording head can be performed to prevent the formation adequate meniscuses at the ink ejecting section of the recording head or in that the ink can not be satisfactorily supplied to the recording head. This also disallows the ink to be used completely.
Some ink tanks have a configuration in which ink is contained in a bag-shaped member, and the material and shape of which are appropriately selected to generate a negative pressure by the bag-shaped member itself and which becomes flat with no space left therein when the ink is completely used up, but there are limitations on the shape of such a bag-shaped member. Therefore, when such an ink tank is configured to be contained in a box-like housing, the configuration of the bag-shaped member does not fit the interior of the housing completely even when it is charged with ink, and the volumetric efficiency of the ink tank is low with respect to the entire space available therein. Such a bag-shaped member also has a problem in that its performance of supplying ink to a recording head can be reduced and in that it can make an ink ejecting operation of a recording head unstable when ink is nearly used up because of a high negative pressure.
Several mechanisms have been proposed as follows to prevent magnitude of a negative pressure being too much greater than the predetermined level.
For example, Japanese Patent Application Laid-open No. 7-125240 (1995) and Japanese Patent Application Laid-open No. 7-125241 (1995) have disclosed mechanisms in which a hydrophobic film and a tubular vent port are provided in a tank, and a spherical body is disposed in the tube to introduce air into the tank when a negative pressure therein increases. That is, those publications have disclosed mechanisms which have a tubular vent port (boss) that establishes communication between the outside and inside of a container and in which spherical body having an outer diameter smaller than an inner diameter of the boss is attached to a plurality of projecting ribs provided on an inner wall of the boss to form a substantially annular orifice with the spherical body and the boss. The size of such an orifice is chosen such that a small amount of ink is kept in the orifice as a liquid seal because of the capillarity of ink. The orifice is configured such that a negative pressure in the container overcomes the capillarity of ink to disable the liquid seal when it nearly reaches the limit of an operating range of the recording head.
Japanese Patent Application Laid-open No. 6-183023 (1994) has disclosed a mechanism in which a plate-like member having a hole and a plate having a protrusion are provided in a face-to-face relationship in an ink bag constituted by a flexible sheet with a spring member disposed between the plates and in which the protrusion enters the hole when an internal negative pressure exceeds a predetermined value to separate the plate having the hole and the flexible sheet from each other, thereby introducing air in the tank. In this mechanism, the plate having the hole and the flexible sheet come into tight contact with each other after air is introduced, and leakage of ink is prevented by an ability for holding ink meniscuses or a liquid seal formed between those elements.
However, those methods require a plurality of parts in a region where air is introduced, and the structure of such a region has therefore become complicated.
When a pressure in a container T having a certain amount of air introduced therein becomes extremely high as a result of an ambient change (a reduction of the atmospheric pressure or a temperature rise) as shown in FIG. 1A, ink is pushed out from the container as shown in FIG. 1B, which can result in leakage of ink through an ink ejection port N or a vent hole A when the container is used in an ink jet recording head. When a liquid is contained in a bag-shaped member constituted by a flexible sheet, although expected is a certain degree of buffering effect that moderates an increase of a pressure therein by accommodating expansion of air which results in a pressure reduction, such an effect is limited.
In the configuration disclosed in Japanese Patent Application Laid-open No. 7-125240 (1995) or Japanese Patent Application Laid-open No. 7-125241 (1995), an enclosed system is established by balancing a force originating from ink meniscus formed in the region of the annular orifice and a negative pressure provided by the spring. Although the mechanical configuration is relatively simple, it is insufficient in stability in maintaining the enclosed system. Specifically, a problem arises in that contained ink can leak out because of breakage of a liquid seal that is attributable to various conditions such as a difference between air pressures inside and outside the container, a reduction of the viscosity of ink resulting from an increase in the temperature of ink, a shock or drop that occurs when the ink tank is handled alone, and acceleration that occurs during main scanning according to the serial recording method, in particular. Further, a liquid seal is vulnerable to humidity changes such as drying, which causes variations in the operation of introducing air bubbles and consequently reduces the capability of supplying ink to a recording head and hence the quality of recording.
It is assumed that the above publications have disclosed configurations in which an entrance maze serving as an overflow container and ensuring a humidity gradient is provided contiguously with a boss in order to prevent such problems, but the configurations become complicated accordingly. Further, since the other end of the channel in the form of a maze is always in communication with the atmosphere, a certain degree of ink evaporation is unavoidable.
When ink in the container is used up, outside air is abruptly introduced to eliminate the negative pressure in the container. This can cause ink remaining in the region of the recording head to leak out through the ejection port, and the residual ink can leak out through the annular orifice that no longer forms meniscus.
Further, in those examples of the related art, there is provided an opening section for directly introducing the atmosphere into an ink tank. As a result, the quantity of gases in the ink tank becomes relatively great in a region in the ink tank where ink is nearly used up depending on the size and position of the opening section, which can result in incomplete holding of meniscuses at the ink ejection port or opening section when the negative pressure is eliminated as a result of introduction of the atmosphere and can therefore lead to leakage of ink or incomplete introduction of the atmosphere.
In addition, breakage of a liquid seal can occur because of various conditions such as a difference between air pressures inside and outside the container, a temperature rise of drop, a shock or drop that occurs when the ink tank is handled alone, and acceleration that occurs during main scanning according to the serial recording method, in particular. This results in a problem in that air can be introduced or ink can leak out conversely even when a pressure in the container has not reached a predetermined value. Further, such conditions can vary depending on the designs of the recording head and ink tank or physical properties of ink, and a problem arises also in that designing must be adequately carried out in accordance with the shape and dimensions of the opening section and the basic configuration of the negative pressure generating mechanism depending on each mode of use.
The above ink tank utilizing a liquid seal for introducing air creates problems such as a reduction of freedom in designing a recording apparatus in addition to problems inherent in it as described above.
Specifically, it is not easy to configure such a liquid seal section as an element separate from an ink tank by making it detachable from the ink tank, for example. In case that the liquid seal section is provided as a separate element, a complicated process or apparatus configuration will be required when attaching the element to an ink tank directly or connecting it to the ink tank indirectly through a tube in order to form preferable meniscus in an annular section as described above taking factors such as a difference between pressures inside and outside the ink tank into consideration.
When the liquid seal section is provided in a position apart from an ink tank with a tube interposed therebetween, the tube must be filled with ink to form meniscus at the liquid seal section. However, the ink in the tube will be returned to the ink tank when air is introduced through the liquid seal section, and a complicated process or configuration will be required to refill the tube with ink thereafter as described above.
The technique disclosed in the Japanese Patent Application Laid-open No. 6-183023 (1994) employs a structure in which air is introduced through a microscopic gap between a thin plate-like member and a flexible sheet. This has resulted in another problem in that a negative pressure becomes unstable when air is introduced because the force for causing separation as described is changed by a capillary force that is generated when a liquid enters the gap.
Further, in order to provide a sufficient buffering function, a member that has extremely low rigidity and that is easy to deform is used as the flexible member for moderating an internal pressure of a container by substantially increasing the volumetric capacity of the container through the deformation of the flexible member itself when the pressure of a gas (air) in the container increases as a result of a temperature rise.
However, since a material having low rigidity used as such a flexible member has a small thickness and exhibits high permeability against gases in general, it is likely to allow a gas to penetrate into a container because of an osmotic pressure of the gas. This has resulted in the possibility of insufficient performance of the buffering function when a liquid is kept in the container for a long time because a gas (air) can penetrate into the container in a quantity that cannot be handled by the buffering function for absorbing expansion of the gas in the container. Therefore, it has been necessary to use a quite expensive material having a metal deposited thereon as the material of the flexible member in order to achieve low rigidity and a reduction in gas permeability at the same time.
From the above, the inventors first found that it is undesirable to eliminate a negative pressure in a liquid container by introducing air into the container and that it is important to return the pressure to a predetermined negative pressure value. Further, the inventors consider that an appropriate amount of air must be introduced for this purpose.
In particular, when a liquid container is used as an ink tank for directly supplying into to an ink jet recording head, it is inevitable to supply ink at a stable rate of flow and in a stable amount to perform recording at a high speed with high quality. For this purpose, it is strongly desired to keep a substantially constant resistance in an ink supply channel against a flow of ink. Therefore, the stabilization of a negative pressure in an ink tank is an important factor and, more specifically, it is important to keep the negative pressure in a predetermined range. For this purpose, a part for introducing air must operate with reliability.
It is also important to allow a liquid to be contained in a container in a proper state by reducing opportunities when those members are subjected to an osmotic pressure of a gas to reduce penetration of the gas into the container and to allow the contained liquid to be supplied with stability.
The invention has been made taking the above-described problems into consideration and achieves at least one of the following aims.
In a configuration of a containing portion of a liquid (e.g., ink) to be supplied to the outside (e.g., a recording head) having a section for generating a required negative pressure and an air introducing section for keeping the negative pressure within a proper range by allowing air to be introduced into the containing section in accordance with an increase in a negative pressure therein as a result of the supply of the liquid, the invention makes it possible to prevent the liquid from leaking out though the air introducing section in any environment of use and storage and to maintain stable negative pressure characteristics regardless of the phase of consumption of the liquid.
The invention provides a liquid container (such as an ink tank) in which introduction of outside air for maintaining a constant negative pressure in the liquid container is performed reliably at adequate timing to stabilize the negative pressure with higher reliability and in which leakage of a liquid through a liquid supply port is prevented even at an abrupt ambient change to avoid wasteful consumption of the liquid eventually, and the invention also provides a liquid-consuming apparatus (such as an ink jet recording apparatus) utilizing the liquid container.
The invention provides an ink tank having a negative pressure adjusting mechanism with which problems inherent in ink tanks as described above utilizing a liquid seal can be solved and with which freedom in designing a recording apparatus can be improved, an ink jet recording head, an ink jet cartridge having the ink jet recording head and the ink tank as integral parts thereof, and an ink jet recording apparatus.
The invention provides a liquid container with a simple structure which absorbs changes in a negative pressure therein as a result of consumption of a liquid to stabilize the negative pressure, which prevents leakage of the liquid through a liquid supply port even at an abrupt ambient change, and which can be manufactured at a low cost, and the invention provides a liquid-ejection recording apparatus utilizing the liquid container.
The invention provides a liquid container a part of which is constituted by a flexible member and a member having high gas permeability, in which a liquid can be properly contained by reducing opportunities when those members are subjected to an osmotic pressure of a gas to reduce penetration of the gas into the container, and from which the contained liquid can be supplied with stability, the invention also providing a recording apparatus utilizing the same.
In a first aspect of the invention, there is provided a liquid container comprising:
a containing portion defining a containing space for liquid;
a liquid supply portion provided with the containing portion and forming a liquid supply port for supplying liquid contained in the containing portion to the outside;
a one-way valve arranged on the containing portion for allowing an introduction of gas into the containing space from outside, and preventing a leakage of liquid and gas to the outside; and
a mechanism having a function for keeping or expanding a capacity of the containing space, wherein
the one-way valve controls a negative pressure in the containing space caused by consumption of liquid in the containing portion.
Here, the mechanism may include a movable member equipped with at least a part of the containing portion displaceably or deformably, and an urging means for urging the movable member in a direction a capacity of the containing space increases.
Further, the containing portion may have a deformable flexible member in a part thereof as the movable member and is configured so that liquid is present inside the flexible member contacting with the outside space.
There is provided a liquid using apparatus connectable with the liquid container according to the first aspect and using liquid supplied from the containing space.
Further, there is provided a recording apparatus comprising means using the liquid using apparatus having a configuration of recording head for performing a recording with ink supplied from the liquid container which contains ink as the liquid.
Still further, there is provided an ink jet head cartridge comprising:
an ink jet head for ejecting ink; and
a liquid container, according to the first aspect, for containing ink as the liquid to be supplied to the ink jet head.
In a second aspect of the invention, there is provided a liquid supplying method for supplying liquid to the outside from a containing portion defining a containing space for liquid through a supply port formed on the containing portion, comprising the steps of:
providing a one-way valve for allowing an introduction of gas into the containing space from outside, and preventing a leakage of liquid and gas to the outside;
providing a mechanism having a function for keeping or expanding a capacity of the containing space, and;
controlling a negative pressure in the containing space caused by consumption of liquid in the containing portion by the one-way valve.
In a third aspect of the invention, there is provided a liquid supply apparatus, comprising:
a containing portion which defines a containing space for liquid and includes a liquid supply portion for forming a liquid supply port for supplying contained liquid to the outside and a gas introduction portion for introducing gas from outside into the containing space;
a mechanism having a function for keeping or expanding a capacity of the containing space; and
a one-way valve having a gas introducing member mountable on the gas introduction portion in which, in the state where the gas introduction member is mounted onto the gas introduction portion, an introduction of the gas is allowed through the gas introduction portion and a leakage of liquid and gas from the containing space to the outside is prevented, and the one-way valve for controlling a negative pressure in the containing space caused by consumption of liquid in the containing portion.
There is provided an ink tank for the liquid supply apparatus according to the third aspect, comprising:
the containing portion for containing ink as the liquid; and
a mechanism having a function for keeping or expanding a capacity of the containing space.
Further, there is provided an ink jet recording apparatus for performing a recording by ejecting ink onto a recording medium by using this ink tank and a recording head for ejecting ink supplied by the ink tank, comprising:
a holder for mounting the ink tank;
a one-way valve for allowing communication of fluid flowing into one direction and preventing communication of fluid toward the other direction; and
a flow path being connected with the one-way valve and being open and closed thereby; wherein
the holder having a member communicating with the flow path and the ink tank having a mounting portion capable of detachably mounting the member of the holder, whereby gas is introduceable thereinto through the one-way valve and the member of the holder.
There is provided an ink jet cartridge, comprising:
an ink tank for constituting the liquid supply apparatus according to the third aspect, the ink tank having the containing portion for containing ink as the liquid and a mechanism having a function for keeping or expanding a capacity of the containing space; and
an recording head for ejecting ink supplied from the ink tank through a communicating path, the recording head being formed integral with the ink tank.
Further, there is provided an ink jet recording apparatus for performing a recording by ejecting ink onto a recording medium by using this ink jet cartridge, comprising:
a holder for mounting the ink jet cartridge;
a one-way valve for allowing communication of fluid flowing into one direction and preventing communication of fluid toward the other direction; and
a flow path being connected with the one-way valve and being open and closed thereby; wherein
the holder having a member communicating with the flow path and the ink tank of the ink jet cartridge having a mounting portion capable of detachably mounting the member of the holder, whereby gas is introduceable thereinto through the one-way valve and the member of the holder.
In a fourth aspect of the invention, there is provided a one-way valve for, mounted on a containing portion which defines a containing space for liquid, allowing an introduction of gas from outside to the containing space and preventing a leakage of liquid and gas from the containing space to the outside, the one-way valve comprising:
a hollow gas introduction member for inserting into the containing space;
a valve chamber communicated with the gas introduction member and having an opening portion which allows an introduction of gas from outside; and
an opening/closing member which is provided with the valve chamber and urged in the direction the opening portion is closed, whereby being activated to open the opening portion if the pressure within the containing space becomes less than the predetermined value.
In a fifth aspect of the invention, there is provided a liquid container, comprising:
a liquid containing chamber having a movable member defining a containing space of liquid at least in part thereof and being deformable according to a supply of the liquid to the outside, and having a liquid supply port for supplying liquid contained therein; and
a valve chamber communicating with the containing space and having a one-way valve which allows an introduction of gas into the containing space form outside and prevents a leakage of liquid and gas to the outside from the containing space; wherein
the liquid containing chamber includes an elastic member for generating an urging force F1 in the direction increasing a content of the containing space, and an urging means for receiving the urging force F1 to urge the movable member with an area S1 against the direction;
the valve chamber includes a valve controlling member for generating an urging force F2 in order to control an opening operation of the on-way valve, and a closing means for receiving the urging force F2 to close the one-way valve by an act of the urging force F2 with an area S2; and
the one-way valve is configured to be open in order to introduce air from outside, assuming that the pressure resulted from the meniscus of the liquid formed in a communicating portion which makes a communication between the containing space and the valve chamber when the liquid is present in the communicating portion is PM, the height between the meniscus and the uppermost of ink in the containing space is h, the density of the liquid is xcfx81, and the acceleration of gravitation is g, respectively; an absolute value of the negative pressure PV=xe2x88x92(F1/S1)+hxc3x97xcfx81xc3x97g+PM acting on the valve chamber satisfies
|PV| greater than |F2|/S2. 
Here, the valve chamber may be configured to have a communication with the containing space at a portion of the liquid containing chamber which retains the introduced gas, and when the following formula
|F1|/S1 greater than |F2|/S2
is satisfied, the one-way valve is open to introduce air from outside.
In a sixth aspect of the invention, there is provided a liquid container, comprising:
a movable member which defines a containing space for liquid and is displaceable according to supply of the liquid;
a liquid supply port for supplying the contained liquid to the outside; and
a one-way valve having a port capable of introducing gas into the containing space and a sealing member for sealing the port; wherein
the one-way valve is opened to introduce the gas when a capacity of the containing space starts to decrease due to a displacement of the movable member according to supply of the liquid and becomes lower than the predetermined value.
In a seventh aspect of the invention, there is provided a liquid container having a liquid supply port for supplying the contained liquid to the outside and a valve chamber equipped with a one-way valve for allowing an introduction of gas into the containing space from outside and preventing a leakage of liquid and gas from the containing space to the outside, the liquid container being generally sealed except for the liquid supply port and the one-way valve, comprising:
a negative pressure generating means for applying negative pressure to the liquid supply from the liquid supply port; and
a negative pressure controlling means for controlling the negative pressure by introducing the gas, wherein
the negative pressure controlling means has a function to prevent a discharge caused by an operation tempting to discharge liquid and gas to the outside therefrom.
In a eighth aspect of the invention, there is provided a liquid container, comprising:
a movable member which defines a containing space for liquid and is displaceable in accordance with a supply of the liquid;
a liquid supply port for supplying the contained liquid to the outside;
an opening capable of introduction of gas into the containing space; and
a valve body for sealing the opening; wherein,
the containing space is configured to maintain the capacity thereof about the predetermined value regardless of a supply of the liquid and an introduction of the gas, after the capacity of the containing space starts to decrease according to the supply of the liquid from the state where the containing space is generally filled with the liquid to be lower than the predetermined value which causes an introduction of gas.
There is provided a liquid using apparatus capable of being joined with the liquid container according to any one of the fifth to eighth aspects, wherein liquid supplied from the containing space is used.
Further, there is provided a recording apparatus utilizing a liquid container according to any one of the fifth to eighth aspects in which an ink as a recording agent is contained, and performing a recording with ink supplied from the containing space.
Moreover, there is provided an ink jet cartridge, comprising:
a liquid container according to any one of the fifth to eighth aspects in which an ink as a recording agent is contained; and
a recording head capable of ejecting ink from an ink ejection port, the recording head being joined with the containing space and the ink being supplied from the containing space.
In the above, an ink as the liquid may contain pigment as a color material.
Incidentally, in the present specification, the wording xe2x80x9crecordingxe2x80x9d means not only a condition of forming significant information such as characters and drawings, but also a condition of forming images, designs, patterns and the like on printing medium widely or a condition of processing the printing media, regardless of significance or unmeaning or of being actualized in such manner that a man can be perceptive through visual perception.
Further, the wording xe2x80x9cprinting mediumxe2x80x9d means not only a paper used in a conventional printing apparatus but also everything capable of accepting inks, such as fabrics, plastic films, metal plates, glasses, ceramics, wood and leathers, and in the following, will be also represented by a xe2x80x9csheetxe2x80x9d or simply by xe2x80x9cpaperxe2x80x9d.
Still further, the wording xe2x80x9cinkxe2x80x9d should be interpreted in a broad sense as well as a definition of the above xe2x80x9cprintingxe2x80x9d and thus the ink, by being applied on the printing media, shall mean a liquid to be used for forming images, designs, patterns and the like, processing the printing medium or processing inks (for example, coagulation or encapsulation of coloring materials in the inks to be applied to the printing media).
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.